WannaBeDrD - 7-6-2011 at 17:10
Can a 5-10% solution of KOH safely be stored in a glass jar?
I've spent two days searching both this forum and Google, but to no avail. I probably just haven't hit upon the magic search phrase.
Thanks
ScienceSquirrel - 7-6-2011 at 18:00
That depends on how on how long you want to store it and how pure you want it to be.
Cold potassium hydroxide of that concentration may absorb water from the air so it might gradually become more dilute depending on relative humidity.
It will also absorb carbon dioxide from the air tp form potassium carbonate and bicarbonate if it can.
It will dissolve a little silica from the glass over time but this is not so significant, it might attack the stopper and seal but this is dependent
on what it is made of.
A hard glass bottle with a polypropylene cap could keep this in for decades, a soft glass bottle with a traditional cork will not achieve much!
WannaBeDrD - 7-6-2011 at 19:06
So what would be the proper storage container? HDPE? PET? Something else?
WannaBeDrD - 7-6-2011 at 20:32
Finally found something. PET would be bad...Sodium and Potassium Hydroxides are used in the recycling process to hydrolyze PET.
LDPE and HDPE should be OK.
This is a cool listing of chemical resistances for plastics. I'm sure there are others...
http://www.calpaclab.com/pages/chart.html
Thanks for the reply ScienceSquirrel.
mr.crow - 8-6-2011 at 06:41
Depends on what you use it for. If it is a 1.000N volumetric solution used for titration then it can't be stored for too long. If it is a general
reagent then absorbing a little water and CO2 is ok. If it drops from 10% to 9.9% it doesn't matter.
HDPE should be fine. Like the bottles for rubbing alcohol. I always wrap the cap with electrical tape to seal it up.
smuv - 8-6-2011 at 15:44
storage in polyolefins is best.